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ZCZC SPCSWOD48 ALL
ACUS48 KWNS 210956
SPC AC 210956
Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0356 AM CST Wed Feb 21 2018
Valid 241200Z - 011200Z
...DISCUSSION...
A significant shortwave trough will eject northeast through the
central Plains and middle MS Valley region (Day 4) Saturday and
Saturday night. Some deamplification is expected, but the trough
will take on a more negative tilt as it approaches the middle MS
Valley. GFS is still the stronger solution with deeper cyclogenesis
and suggests potential for a slightly more robust severe threat. In
either case a forced line of potentially strong to severe storms
might evolve in vicinity of cold front initially over northeast TX,
before spreading into the lower MS and TN Valley regions as the
low-level jet strengthens and shifts northeast through moistening
warm sector. While vertical shear and overall character of the wind
profiles should be more than adequate for organized severe storms,
primary limiting factor appears to be a marginal thermodynamic
environment given likelihood of widespread clouds and weak lapse
rates.
Some severe threat might linger into Sunday (day 5) over a portion
of the Middle Atlantic, but confidence is not high enough at this
time to introduce a categorical area. Overall severe potential
should remain low day 6 into day 7 as a cold front settles into the
northern Gulf coastal area.

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SIGTOR showing 45% out in parts of the Ms and Ark,30% in parts of the Western Valley,Saturday.The GFS was slightly faster tonight.The VBV that Jeff talked about above is not near as bad today as it's been showing.

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Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0219 AM CST Thu Feb 22 2018
Valid 241200Z - 251200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF
EAST TEXAS INTO THE LOWER MISSISSIPPI...TENNESSEE AND OHIO
VALLEYS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE SOUTHERN PLAINS THROUGH THE OHIO VALLEY AND SOUTHEAST
STATES...
...SUMMARY...
Strong to severe storms will be possible Saturday from a portion of
northeast Texas through the lower Mississippi, Tennessee and Ohio
Valleys.
...Northeast TX into the lower Mississippi Tennessee and Ohio
Valleys...
A significant shortwave trough will eject northeast through the
central Plains and middle to upper MS Valley region Saturday and
Saturday night while taking on a negative tilt. In response to
forcing accompanying this feature, a surface low initially over the
southern Plains will deepen as it develops northeast through the
middle MS Valley, eventually reaching the Great Lakes toward the end
of the period. Warm front extending east from the surface low will
move northward, reaching the OH Valley Saturday night. A cold front
initially across west TX will advance through the Southern Plains
and middle to lower MS Valley during the day reaching the OH and TN
Valleys Saturday night. A strengthening low-level jet resulting from
the deepening cyclone will transport richer gulf moisture northward
with low 60s F dewpoints as far as the OH Valley and mid to upper
60s from east TX to the lower MS Valley. However, instability will
probably remain marginal due to widespread clouds and modest lapse
rates with MLCAPE likely to remain below 1000 J/kg over most of the
warm sector.
A forced line of potentially strong to severe storms should evolve
in vicinity of cold front initially over north central or northeast
TX into southeast OK during the day. Activity will subsequently move
into the lower MS, TN and OH Valley regions as the low-level jet
strengthens to 60+ kt and shifts northeast through moistening warm
sector. Vertical shear and overall character of wind profiles will
be more than adequate for organized severe storms, with potential
for LEWP, bowing segments and a few embedded supercells capable of
damaging wind and a few tornadoes. An upgrade to higher
probabilities might be needed in later outlooks once uncertainties
regarding the thermodynamic environment have been mitigated.

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Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1251 AM CST Fri Feb 23 2018
Valid 241200Z - 251200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE ARKLATEX INTO THE LOWER TO MID MISSISSIPPI VALLEY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
NORTHEAST TEXAS INTO THE LOWER TO MID MISSISSIPPI AND TENNESSEE
VALLEYS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY NORTH-NORTHEASTWARD
INTO THE OHIO VALLEY...
...SUMMARY...
Scattered strong to severe thunderstorms are expected to develop and
move east-northeastward on Saturday from parts of northeast Texas
into the lower to mid Mississippi and Tennessee Valleys. Tornadoes,
wind damage and hail will be possible with the more intense storms.
...Arklatex/Lower to Mid Mississippi Valley/Ohio Valley...
An upper-level trough will move from the Rockies into the Great
Plains on Saturday. Ahead of the system, a moist airmass will be in
place at the start of the period from East Texas extending
northeastward into southern parts of the mid Mississippi Valley.
Elevated thunderstorms should be ongoing in the vicinity of
Dallas/Fort Worth around 12Z. This convection is forecast to expand
in coverage, moving eastward into the Arklatex where a 40 to 60 kt
low-level jet will strengthen. As surface temperatures warm during
the day, the convection is forecast to gradually become
surface-based. A cluster of storms should become organized as it
moves east-northeastward from far northeast Texas across southern
and eastern Arkansas during the afternoon. This activity should
eventually affect northwest Mississippi, western Tennessee and far
western Kentucky by evening.
Ahead of the system moving into the Great Plains, a 75 to 90 kt
mid-level jet will translate east-northeastward from the southern
Plains into the Ozarks. This feature will create strong deep-layer
shear profiles favorable for severe storms along the southeastern
periphery of the mid-level jet. Strong lift and 0-6 km shear in the
55 to 65 kt range, evident on forecast soundings, will support
supercell development. Supercells that interact with the western
edge of the low-level jet from far northeast Texas into southern and
central Arkansas will have tornado potential. NAM forecast soundings
across southern Arkansas at 21Z on Saturday show 0-3 km storm
relative helicities near 300 m2/s2 which should be favorable for a
few strong tornadoes. Supercells and the stronger multicells
embedded in the cluster should also be associated with wind damage
and hail. The wind damage threat could increase as the cluster
transitions into a line segment, moving eastward from eastern
Arkansas into northwest Mississippi, western Tennessee and far
western Kentucky by Saturday evening.

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SPC is amped 300 m2/s2 and strong tornado wording. They seem to like southern Ark. Probably for instability. I still like the low level kinematics near Memphis better. Issue will be getting things juxtaposed right (or wrong depending on your perspective).

I see the main line starting over the Ozarks which is a no-fly zone - worse than almost anything this part of Dixie. Lead line might go near Memphis but too early for me to get there and probably before strongest kinematics anyway. Finally storm motion will be very fast, hard to manage. Given that Kansas is at Texas Tech mid-afternoon, and the game is for the Conference Title, I will not chase this set-up.

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ay 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CST Fri Feb 23 2018
Valid 241200Z - 251200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE
ARKLATEX TO THE LOWER OHIO VALLEY...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTH TEXAS
TO THE OHIO VALLEY...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
TEXAS/LOUISIANA COASTS TO THE MIDWEST...
...SUMMARY...
Scattered to numerous thunderstorms will develop across the southern
Plains Saturday morning and shift northeastward towards the Ohio
Valley through Saturday night. Several of these storms will likely
be severe, with damaging winds and a few tornadoes being the primary
threat. A few instances of large hail will be possible as well.
...Synopsis...
Within a cyclonic-flow regime across the western US, a robust
shortwave trough will eject northeast across the central Plains,
while acquiring a negative tilt as it approaches the upper Midwest.
In response, mid-level heights will fall over much of the Plains and
Mississippi Valley through the day. The surface pattern will feature
a deepening low lifting north from the Mississippi Valley towards
the upper Great Lakes. Trailing to its south, a cold front will
accelerate eastward towards the Ohio and Tennessee Valleys, while
the preceding warm sector advances northward from the Mid-South to
portions of southern Illinois, Indiana, and Ohio.
...Arklatex to the Ohio Valley...
As the aforementioned shortwave trough continues northeast towards
the upper Midwest, a strong low-level jet is forecast to organize
across the Arklatex through the mid-day hours, before strengthening
and translating northeast towards the Ohio Valley through the
overnight hours. In conjunction with this evolution, the surface
warm sector (characterized by dew points in the lower/mid 60s along
its northern fringes) will stream northward, reaching areas from
southeastern Missouri to southern Indiana through the period. South
of the warm front, despite little/modest low-level heating and
related buoyancy, favorably moist low levels should support upwards
of 1000 J/kg of MLCAPE across parts of the Mid-South by afternoon,
with values decreasing to 200-400 J/kg across the Ohio Valley.
Countering these lower values of buoyancy, a strong kinematic
profile will evolve across much of the region, especially from
northern Arkansas to the lower Ohio Valley. Within this region,
925-850mb flow around 60-70 kt will contribute to sizable values of
storm-relative helicity through the evening hours. In turn, as a
narrow band of convection organizes from the Arklatex to the Ozarks
through the day, shear profiles should encourage several bowing/LEWP
structures, with embedded supercells possible. Furthermore, forecast
soundings and high-res guidance depict a considerable component of
low-level shear perpendicular to several bowing segments, enhancing
the potential for tornadoes -- a few of which could be strong --
during the afternoon and evening hours. These cells will then race
towards the Ohio and Tennessee Valleys during the evening and
overnight. Moist adiabatic low-level profiles, while not conducive
for high values of buoyancy, may still prove favorable for a few
swaths of damaging winds (with an attendant line-embedded tornado
threat), as any low-level rotating elements will enhance upward
vertical motion and convective intensity.
Outside of the main band of convection, although forcing for ascent
will not be particularly strong earlier in the day, an isolated
discrete supercell or two may form across the Mid-South within
warm/moist low-level confluence Saturday afternoon. Favorable
storm-relative helicity and effective shear would support a
conditional damaging wind and tornado threat during this time frame
as well.

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Euro is pretty stout later next week too, but in the Deep South which is more favored by climo. I'm not sure whether to wish for that or pray against it.

TODAY Mid South I am reluctantly staying home. Some CAMS - convective allowing (high res) models show lead cells. My gut says they will not be supercells. They are ahead of the best low level shear. If I'm wrong, it would not be the first time LOL. NAM and ARW versions of the WRF both have mainly linear. HRRR is the one introducing cells ahead, but I'm not biting.

Plus I got two very important college basketball games on ESPN mid-afternoon. Also, that thing next week...

UPDATE: Clarksville tornado warning had exceptionally long lead time from the NWS. Great job in Dixie at night!

On a brighter note, Kansas is now the solo record holder for consecutive regular season Conference Championships!

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That does not look good. Any updates on those cells and what happened on the ground?

Those super cells earlier produced some minor wind damage reports but nothing tornadic fortunately. Probably haven't seen the last FFWs tonight though. Some serious heavy rainfall in these cells over NE AL and NW GA.

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MESOSCALE PRECIPITATION DISCUSSION 0054
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1132 PM EST WED FEB 28 2018
AREAS AFFECTED...ARKLATEX, AR, NORTHERN MS, & TN
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 010431Z - 010901Z
SUMMARY...A BAND OF HEAVY RAIN IS EXPECTED TO IMPACT THE REGION
INTO THE EARLY MORNING HOURS. LOCAL AMOUNTS OF 3-4" OVER
SATURATED SOILS IS EXPECTED TO LEAD TO AND/OR PROLONG FLASH
FLOODING.
DISCUSSION...A BROAD OVERRUNNING PATTERN HAS SET UP FROM NORTHEAST
TX ACROSS AR AND EXTENDING INTO TN WITHIN A REGION OF OVERLAPPING
850 HPA, 750 HPA, AND 650 FRONTOGENESIS PER THE 18Z GFS GUIDANCE.
PRECIPITABLE WATER VALUES OF 1.5-1.7" ARE SEEN HERE PER GPS
VALUES. THE ATMOSPHERE IS SATURATED AS THE MID- AND UPPER-LEVEL
FLOW HAS A FETCH FROM OFFSHORE BAJA CALIFORNIA WHILE THE LOW-LEVEL
INFLOW IS OFF OF THE GULF OF MEXICO. THE WIND FLOW IS FAIRLY
UNIDIRECTIONAL WITH HEIGHT OUT OF THE WEST-SOUTHWEST ABOVE 2,000
FEET PER THE LITTLE ROCK AR VAD WIND PROFILE.
WHILE MUCAPE VALUES OF 500+ J/KG ARE SEEN ACROSS NORTHEAST TX,
PLACES FARTHER AFIELD ACROSS AR AND NORTHERN MS HAVE VALUES OF
100-200 J/KG PER SPC MESOANALYSES. WHILE THESE VALUES ARE MEAGER,
SOIL CONDITIONS OVER A VAST PORTION OF THE AREA ARE SATURATED DUE
TO RAINFALL BEING 300-700% OF NORMAL OVER THE PAST COUPLE WEEKS,
WITH THE LARGEST DEPARTURES ACROSS CENTRAL AR, PATCHES OF
NORTHEAST TX AND SOUTHEAST OK. EVEN WITH THIS LITTLE INSTABILITY,
HOURLY RAIN RATES OF 0.5" ARE POSSIBLE WHICH WOULD COMPROMISE
SATURATED SOILS. THREE HOURLY FLASH FLOOD GUIDANCE VALUES ARE
PRACTICALLY ZERO ACROSS SOUTH-CENTRAL AR AND ARE LOW FROM THE
ARKLATEX ACROSS MUCH OF TN. THE MESOSCALE GUIDANCE ADVERTISES
LOCAL AMOUNTS IN THE 3-4" OVER THE MOST SENSITIVE AREA IN AR WITH
LOWER, THOUGH STILL THREATENING, AMOUNTS EXTENDING INTO CENTRAL
TN. FLASH FLOODING IS CONSIDERED LIKELY.

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Hydrologic Outlook

Hydrologic Outlook
TNZ005>011-023>034-056>066-075-077>080-093>095-020515-
Hydrologic Outlook
National Weather Service Nashville TN
1106 AM CST Thu Mar 1 2018
...Spring Flood Outlook...
...Above Average Risk for Flooding This Spring Across Middle
Tennessee...
Existing Conditions...
Middle Tennessee and much of the Mid-South have been dealing with
recent heavy rainfall, resulting in an elevated flood threat for
the area in the short-term. Recent temperatures have been above
normal as well, and many trees and plants are coming out of winter
hibernation. The warmer and wetter trend is expected to continue
this spring creating an above average risk for future flooding.
Streamflows...
Current streamflows are well above normal in due to recent
rainfall, with many rivers above Flood Stage. Water levels on
these rivers, along with the smaller creeks and streams will
subside over the next few days but levels on the lower reaches of
the Cumberland River and Tennessee River will remain high through
the first next week or two of March.
Rainfall...
Precipitation has been near to above normal for most of the fall
and winter, with January being the only significantly dry month
across the area. Here are some rainfall totals across Middle
Tennessee...
Nashville Clarksville Crossville
October 3.48 (+0.44) 7.18 (+3.27) 6.23 (+3.19)
November 4.46 (+0.15) 2.34 (-2.24) 4.24 (-0.86)
December 4.56 (+0.32) 4.38 (-0.65) 4.56 (-0.39)
January 1.63 (-2.12) 3.59 (+0.28) 1.68 (-3.08)
February 10.91 (+6.97) 9.71 (+5.54) 10.48 (+6.02)
Climate Outlooks...
The National Weather Service Climate Prediction Center indicates
there is a higher probability of above normal temperatures and
above normal precipitation across the area for the months of
March, April, and May.
Summary...
Overall, the spring flood threat across Middle Tennessee is well
above average in the short-term due to the ongoing flooding and
the saturated grounds. An early green-up of vegetation will help
diminish the flood threat for the rest of the spring, however,
the higher probability above normal precipitation creates an above
average risk for flooding through the end of May.
$$

It's still there, but some what better signs but a day later than the earlier map,though it's not really that far off.Trough going through East Asia with a system going through China into the Yellow Sea.This would pump up the heights into China and Mongolia which should if it works out would pump up a +PNA ridge if it were to correlate right.Teleconnection would also support a +PNA ridge mid month,we'll see